Ivacaftor (trade name Kalydeco™) is a potent and selective CFTR potentiator approved for the treatment of adult patients with G551D mutation of cystic fibrosis. Ivacaftor is chemically known as N-(2,4-di-tert-butyl-5-hydroxyphenyl)-1,4-dihydro-4-oxoquinoline-3-carboxamide and has the following structural formula:

U.S. Pat. No. 7,495,103 (hereinafter referred to as the '103 patent) relates to modulators of ATP-Binding Cassette (“ABC”) transporters or fragments thereof, including Cystic Fibrosis Transmembrane Conductance Regulator, compositions thereof, and methods therewith. '103 also relates to methods of treating ABC transporter mediated diseases using such modulators.
U.S. Pat. No. 8,476,442 (hereinafter referred to as the '442 patent) provides a process for the preparation of a compound of Formula 1, comprising coupling a carboxylic acid of Formula 2 with an aniline of Formula 3 in the presence of a coupling agent.

U.S. Pat. No. 8,163,772 discloses salts and co-solvates of N-[2,4-bis(1,1-dimethylethyl)-5-hydroxyphenyl]-1,4-dihydro-4-oxoquinoline-3-carboxamide, including crystalline forms thereof.
Zhang, et al., in Cryst Eng Comm (2012), 14(7), 2422-2427 describe an effort to create novel solvates of Ivacaftor, formed with 2-methylbutyric acid and isobutyric acid respectively, in pursuit of a more robust and reliable scale-up process. The solvates were characterized by X-ray crystallography, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and dynamic vapor sorption. The vapor sorption analysis showed the isobutyric acid solvate to be less stable than the 2-methylbutyric acid solvate, which became the focus of subsequent investigations. The 2-methylbutyric acid solvate was administered to rats and dogs in a series of pharmacokinetic studies, and showed excellent in vivo bioavailability. Thus, using liquid-state co-formers led to a solid form that is bioavailable, as well as stable and processable, suggesting that using such liquid-state co-formers could potentially benefit pharmaceutical development more broadly.
U.S. Pat. No. 8,410,274 relates to solid state forms of N-[2,4-bis(1,1-dimethylethyl)-5-hydroxyphenyl]-1,4-dihydro-4-oxoquinoline-3-carboxamide, pharmaceutical compositions thereof and methods therewith
U.S. Pat. No. 8,471,029 relates to solid state forms of N-[2,4-bis(1,1-dimethylethyl)-5-hydroxyphenyl]-1,4-dihydro-4-oxoquinoline-3-carboxamide, pharmaceutical compositions thereof and methods therewith.